In the stress-management classes Debbie Mandel teaches, parents often tell her about their struggles to combine work and home. Ranking high on their list of challenges is the cellphone.

"Most of the complaints are about how it intrudes on their home life," says Ms. Mandel, of Lawrence, N.Y. "They get called in the middle of the night. The phone is always ringing about minute issues. They ask me, 'How do we deal with that?' "

It's a question on many people's minds these days. A study in the December issue of the Journal of Marriage and Family finds that cellphones and pagers interfere with family life by bringing job worries and problems home. Interviews with working couples — many with children — revealed that cellphone use tends to decrease family satisfaction and increase distress. "People felt they couldn't turn them off," says Noelle Chesley, a sociologist at the University of Wisconsin-Milwaukee, who conducted the study. "I couldn't find evidence of benefits."

Although cellphones give workers the illusion of staying connected with both employers and family members, Mandel often sees a different reality. One mother in her stress-management class boasted that her cellphone enabled her to attend all of her daughter's school activities. "I don't miss anything," she told the group. "Yes, you do," Mandel countered, explaining that when the woman went on a hay ride with her daughter and other children, she spent the whole time on the phone. "Her body was present, but she wasn't there emotionally," Mandel says. "That sends a very ambivalent statement to a child. Sometimes it's better not to be there. To be on the phone with business is ignoring the child."

Some 'addicted' to staying in touch

This "absent presence," as sociologists call it, can also occur when workers with cellphones care for older relatives. "One elderly parent was annoyed," Mandel says. "She told her daughter, 'You trivialize me. You are not giving me your full attention. I'm not important to you. I'm competing for your time.' "

Employees feel more pulled between work and family than ever before, observes Ellen Galinsky, president of the Families and Work Institute in New York. As a result, she sees "an addictive quality to being in touch and worrying that you're going to be out of touch."

As the owner of a large collection agency in Las Vegas, David Stone knows that tug. He tries not to answer his phone at night. But he always thinks he has missed something vitally important for business. "During dinner and on weekends, my wife will roll her eyes and say, 'David, it's not that important.' She's always right. It might just be a business friend calling to see if I'm available for lunch."

At the same time, Mr. Stone emphasizes the benefits of being connected. Knowing he was reachable let him relax on a recent family vacation in Tahiti, for example.

Gabrielle Torello, a communications consultant in Hackensack, N.J., and the single mother of two young boys, calls her cellphone "an invaluable tool, but also the bane of my existence."

Yet like most parents, Ms. Torello would not be without her cellphone. "As difficult as it may be to field messages from an anxious editor at the playground or to sneak out of a meeting to whisper consolation to a 7-year-old frustrated by homework," she says, "having a cellphone allows me to keep in touch with all of the various and equally important aspects of my busy life."

For employees on electronic leashes, cellphones and pagers raise questions about who draws the line between work and home, and where that line is.

Ms. Chesley frames the issue this way: "What are the norms in your workplace about getting calls on your cellphone after hours? Who provides the technology? Is it your cellphone or your employer's? Are individuals buying these themselves, wanting to be accessible to an employer? That has huge implications for family life. The social norms we're developing are really targeted toward increasing access, not toward denying access."

The problem of boundaries became evident to Christena Nippert-Eng when she took her children to a museum. A father was on his cellphone discussing business for several hours. Every time his child would say, "Oh Dad, look at this!" the man would motion that he was busy.

Parents' multitasking leaves kids out

"Families are going to have to step up and address those issues," says Professor Nippert-Eng, a sociologist at the Illinois Institute of Technology in Chicago. "Kids often don't have a lot of power to force their parents' attention on them."

That lack of attention, whatever the reason, can have serious consequences. Nippert-Eng points to out-of-control children on reality shows such as Supernanny and Nanny 911 as warning signs. "Children are starting to engage in very destructive behaviors to demand parents' attention," she says.

As a publicist at Pace University in Pleasantville, N.Y., Cara Halstead Cea must be available by cellphone around the clock. Although reporters and professors sometimes call during family gatherings or her son's baseball games, she finds a bright side.

"The phone affords me flexibility that I would not otherwise have," she says. "If I need to take an extra hour or two for personal business during the week, I — and my bosses — have the peace of mind of knowing that I can be reached if I am needed."

But sociologist Chesley offers a caution about such trade-offs. "This 24/7 access may be a high price to pay for getting a little bit of flexibility at the workplace — to get an hour off from your workday to take your kid to an after-school program, or whatever it is you're doing."

Technology may be the answer, too

While praising electronic tools for helping people to lead productive lives, Jeff Kaye, CEO of an international recruiting firm in Dallas, also sees a downside. "We've become multitaskers," he says. "I can play with my kids while checking e-mail. But rather than becoming more effective, we're losing our ability to concentrate and focus. You do two things with average effectiveness, as opposed to doing one thing with superior effectiveness and then moving on to the second task. How much time did we actually save?"

Round-the-clock connections offer other challenges for Patricia Baronowski of New York, who works in investor relations with international clients.

"I used to keep my BlackBerry on vibrate, which was causing a little tension at home since it was buzzing throughout the night," she says. Now she checks it before she goes to bed and when she wakes up. Clients and her employer know that if something is critical they can phone.

Ultimately, Nippert-Eng says, users of cellphones and pagers must speak up about the challenges they face. "Employers, employees, and family members have to be willing to address boundary issues, sometimes in very confrontational ways. Workers might have to say, 'I'm just not going to answer this cellphone.' "

Even these devices themselves can be part of the solution, says Larry McCallum, a family life professor at Augustana College in Rock Island, Ill. "The real advantage of the newer technology is that, for the most part, it allows me to control most of the negative factors. Most cellphones have caller ID, so I can decide whether to answer a particular call. My father once told me, 'The phone doesn't care whether it gets answered.' The beauty of the system is in the hands of the user."